Pueblo Bonito

Welcome to Pueblo Bonito

To use this trail guide, follow the numbered stops along the trail
which correspond to the numbers in the text. While exploring
Pueblo Bonito, this guide will enable you to recognize several
unique characteristics of Chacoan architecture.

The trail through Pueblo Bonito is 0.6 mile long. The gravel trail
that goes along the southeast corner of the ruin is wheelchair
accessible but assistance is recommended. To reach this alternate
route, follow the south wall past Stop 18 to the plaza entrance.

The archeological resources in Chaco Culture National Historical
Park are fragile, irreplaceable, and a significant part of our
cultural heritage. The park received international recognition
for the cultural resources it contains when Chaco was designated
a World Heritage Site in 1987. You can help us protect and
preserve this part of our global cultural heritage by following
these basic rules:

Stay on the designated gravel trails.

Do not walk, climb, stand, sit, or lean on the walls.

Do not deface, add to, or alter the rock art.

Do not collect pottery or other artifacts anywhere in the park.

If we all take responsibility
for these resources, they will be here for the education and
enjoyment of future generations.

For your safety, do not climb canyon walls, or onto the mesa except
via a designated trail. Children should remain with the guardian
responsible for their safety.

Pets are not allowed in the ruins.

The name Pueblo Bonito is Spanish for "beautiful
town." Carravahal, a guide from San Juan Pueblo,
provided Lt. James Simpson with the name during a
military expedition that came through Chaco in
1849. Following the expedition, Simpson published
the first detailed description of the ruins in
Chaco Canyon.

Anasazi, a Navajo word which translates as "Ancient
Ones" or "Ancient Enemies," is the term
archeologists use to refer to the culture that began
about 2,500 years ago and was centered in the Four
Corners region. The Anasazi Indians were the builders
of the large pueblos that were constructed in Chaco
Canyon from approximately A.D. 850 through 1150.

Pueblo Bonito is the most celebrated and most thoroughly
investigated site in Chaco Canyon. Constructed in
stages over a thousand years ago, Pueblo Bonito
epitomizes the great pueblo architecture found
here. Archeologists specializing in Chacoan archeology
use the term "great house" to describe large sites like
Pueblo Bonito. Great houses display a particular set of
attributes, including planned layouts, multi-story
construction, distinctive masonry, very large rooms, and
circular subterranean chambers called "kivas." Pueblo
Bonito exhibits all of the characteristic elements of
great house construction, all of which you can see along
this trail.

1
Chacoan walls are referred to as "core-and-veneer" masonry,
and are a hallmark of great house construction. You are
looking at the facing stones of the wall (the veneer).
The core consists of roughly shaped pieces of sandstone laid
in mud mortar, which is faced with carefully selected shaped
stones to create the veneer. There were
several types of veneers used in great house construction,
and they changed over time. Today these pattern variations
in veneer provide archeologists with a tool for dating site
construction.

After the walls were built and roofed, a plaster coating was
applied over most of the walls that concealed this fine
stonework. This helped protect the mud mortar from rain. It
also decreased maintenance because it is easier to reapply
mud plaster than to repair the mortar joints of the walls.

Walking up the trail to the next stop, you will see several
mounds on your right. These mounds contain construction
debris. The large mound closest to the cliff conceals a
great house, and in the mounds between Pueblo Bonito and
Chetro Ketl, there may be portions of a masonry wall that
would have connected these two structures during their
occupation.

2
These enormous blocks of sandstone are what remain of
Threatening Rock. Prior to its collapse in 1941, the rock
was a detached segment of the cliff wall that was separated
from the cliff by a wide crack. It measured about 97 feet
high, 140 feet long, 34 feet thick, and weighed an estimated
30,000 tons. Looking along the canyon wall behind you, you
will see a massive vertical boulder that resembles Threatening
Rock before it fell.

The Anasazi builders chose this location even though they
recognized the threat of a fall. They built a supporting
masonry terrace below the rock, which slowed the erosion of
soil from below the rock, delaying its collapse. To your
right, you can see what remains of this terrace.

3
The imposing cliffs surrounding the canyon provided the stone
from which the Chacoans built the impressive structures that
are found here. Two types of stone were used for
construction. The first was a hard, dark brown stone quarried
from the upper canyon walls. The second was the blocky, light
tan stone that is found along the lower walls of the
canyon. The laminated dark brown stone used in earlier
construction appears to have been the preferred building
material. It is harder and breaks more readily at right angles
to the bedding plane. This provided the builders with usable
pieces that could be easily shaped and incorporated into the
intricate stone patterns found in these walls.

4
From here you can see the large scale and geometric design of
Pueblo Bonito. As with most of the other great houses in the
canyon, the layout was the result of several building stages
and was not a single construction event. From initial
construction in the middle of the ninth century, three
hundred years elapsed before the present form of Pueblo Bonito
was realized.

The number of rooms in this structure suggests that many people
lived here. The first archeologists working in Chaco estimated
a population of 20,000 to 30,000 for the entire canyon. These
estimates were based on the number of rooms in all of the known
sites in Chaco. With continuing archeological research,
population estimates have been lowered to between 4,400 and
6,000 people. The lower estimates are based upon a variety of
approaches for determining population size.

The number of known firepits, the amount of arable land, and the
quantity of pottery vessels are some of the data that have been
used to estimate population.

5
This broken cross section of wall displays its massiveness and
how well it was designed. The height of the first story
determined the width of the wall. Wall width decreased with
each additional story, lightening the load on the massive
base. This type of wall construction ensured strong and stable
walls at heights of four or five stories. Decreasing wall
widths also demonstrate advance planning on the part of the
builders. Second and third stories were planned before the
first story was built.

Great houses were built more substantially than other Anasazi
structures in the San Juan Basin, but it is not certain for
what purpose. Substantial walls were necessary for
multi-storied design, but the overall massiveness of the
structures may have served other functions. Pueblo Bonito,
along with the other great houses found here, may have been
used primarily for religious or political functions, rather
than serving individual family needs. The massive scale and
attention to detail in construction also reduced building
maintenance, which would have been particularly important if
the resident population was small or seasonal. Whatever the
reason, substantial portions of the great houses in the
canyon are still intact eight-hundred-years later because
they were so well constructed.

6
This back wall was built during the second construction phase
at Pueblo Bonito, approximately A.D. 1040 to 1050. It included
a row of rooms around the exterior of the first phase rooms,
creating a new back wall. The earlier rooms did not have
exterior doorways, so access to the new arc of rooms was not
possible. There were interior doorways between all the new
rooms and several doorways in the new exterior back wall.

When these rooms were excavated, many of them contained
shelves or platforms across the short axis of the room. These
"roomwide" platforms were constructed midway between the floor
and ceiling, extending from the side wall about four to five
feet towards the center of the room. One interpretation of
these platforms is that they functioned
as shelves, measurably increasing the storage capacity of a
room. These features and the restricted accessibility to
these rooms, have led others to suggest they may have been
used as sleeping platforms. There is no conclusive
archeological evidence regarding their use.

7
The doorways to your right lead into rooms that were used by
Richard Wetherill at the turn of the century. Wetherill, who
was a rancher and an archeologist, and George Pepper, from
the American Museum of Natural History, were the first to
excavate at Pueblo Bonito. After they completed their
excavations in 1899, Wetherill remained in the canyon,
homesteading and operating a trading post until his death in
1910.

Wetherill and Pepper began their excavations in Pueblo Bonito
in 1896, and by the time they were finished, they had excavated
190 rooms. They located, photographed, and mapped all of the
major structures in the canyon. In addition, they recorded
Anasazi irrigation systems, stairways, roads and water
catchment areas, and sponsored other researchers including a
physical anthropologist and a geologist. Overall, they
contributed immensely to the early archeology of Chaco Canyon.

8
This is the oldest section of Pueblo Bonito, dating from
about A.D. 850 to the late 900s. This early construction
consisted of about one hundred ground-floor and upper-story
rooms, including some sections that were three stories
high. Three to five round pit structures (kivas) were built
in front of the multi-storied, crescent-shaped block of
rooms, completing this stage of construction.
As with most great houses, this early section was incorporated
into the bulk of the structure during subsequent stages of
construction. Several different masonry styles are
represented in these walls including the earliest type that
was used in great house construction. Identified as Type I,
it is distinguished by thin rectangular-shaped pieces of
sandstone laid in mud mortar. Type I Walls required more
maintenance than later types because the mud mortar joints
were larger. When exposed to the elements, it would
have been necessary to regularly repair mortar damage to
maintain the wall.

9
This open area is well defined by multi-storied roomblocks
to the north, east, and west, and by a singlestory row of
rooms to the south. It is referred to as the plaza, which
is a term borrowed from later pueblo architecture used for
a similar feature. Along the front of the roomblocks,
large firepits were dug, and several kivas were constructed
in the plaza. The archeological record provides few clues
to the specific use of the plaza area, but based upon modern
day use, a great deal of activity took place here. Today,
plazas provide a place for people in the community to gather
for informal activities as well as ceremonial events.

The plaza of Pueblo Bonito is divided into eastern and western
halves by a central dividing wall that is aligned with true
north. There was only one entryway into the plaza, which is
located in the southeast corner of the western half of the
plaza. (The present opening in the eastern section resulted
when a room collapsed.) When the original entrance was first
constructed, it was over seven feet wide. During a later
construction phase it was remodeled and reduced to a door less
than three feet wide, and even this small door was subsequently
blocked. One of the original excavators interpreted this as a
defensive measure, suggesting there was a pressing need for
this deliberate and progressive closing in of the pueblo.

10
This very large, round subterranean structure is a great
kiva. They are characteristic of great house construction
and include a set of highly standardized architectural
features. These include a low masonry bench around the base
of the room, raised floor vaults, a raised firebox and deflector, pits for
seating four wooden posts or masonry pillars used to support
the roof, and an antechamber and entryway at the plaza level
of the subterranean structure.
The size, standardization in
construction, and investment of labor exhibited in great kivas
indicates they may have served a highly specialized public
function that met community-wide needs. In the plaza of Pueblo
Bonito, there were at least three great kivas.

An additional feature that is frequently found in Chacoan great
kivas is a set of wall crypts or niches. Wall niches may have
functioned as depositories for offerings and ceremonial
paraphernalia, or possibly served as open shelves for the
display of ceremonial objects. Supporting evidence for these
interpretations is the recovery of beads, pendants, and
ornaments from the niches in one of the great kivas at Chetro
Ketl. When these niches at Pueblo Bonito were exposed during
the excavation of this great kiva, they were empty.

11
In describing the architecture of the modern Pueblo Indians,
the term kiva is used to refer to round rooms used for
ceremonial purposes. This term has been applied to the round
rooms found in Chaco and other prehistoric sites in the
Southwest. Although it is not known whether the prehistoric
kiva was used exclusively for ceremony, this architectural
form dates back to the earliest Anasazi pithouses, around
A.D. 400.

Neil Judd, who excavated at Pueblo Bonito from 1921 through
1927, identified several features of kivas in Chaco that
distinguish them from kivas in other Anasazi
settlements. Judd defined the "Chaco-type" kiva as including
a low masonry bench encircling the base of the room with a
short recess usually to the south, low masonry boxes called
pilasters built on the bench as roof supports, a firepit, a
subfloor ventilating system, and a sub-floor
vault. Additional research has expanded this list of features
to include the elevation of the room to an above-ground square
enclosure, which can be seen in the kiva to your left, and a
characteristic bench backing referred to as wainscotting. The
kivas in this section of Pueblo Bonito include all of these
features except for the bench backing.

12
In this room, there are remnants of original plaster as well
as primary and secondary roofing beams known in Spanish as
"vigas" and "latillas." Vigas are the primary beams and
carry the weight of the roof. Latillas are secondary supports
and were laid perpendicular to the primary beams. Split
shakes of juniper wood, bark, and matting were then laid over
the secondaries. A layer of clay mortar,
or packed adobe was applied over this, and the surface was
completed with a final layer of sand.

The size of this room is characteristic of the rooms built in
Chacoan great houses between A.D. 900 and 1150, with large
floor areas and very high ceilings. The present surface is
elevated above the actual floor level due to the protective
fill. Before leaving this room, note the masonry-filled
doorways. These can be seen throughout the great houses in
the canyon and are usually the result of architectural
modifications completed by the Anasazi builders. Closing
rooms off could have been done to conserve heat, or it may
have indicated a change in the use of the room, such as from
domestic use to storage.

13
The function or use of a room is often difficult to determine
in prehistoric buildings. One of the ways archeologists try
to determine room function is through architectural features
found at the time of excavation. These may include sandstone
slabs used to grind corn or grains, mealing bins, or
firepits. Another is through examining the artifacts that
are recovered, and studying their placement upon
excavation. The large rooms in this section of the pueblo
would have been inadequate as domestic dwellings. Because
of their size, they would have been difficult to heat, and
they would have been dark because they are interior
rooms. When these rooms were excavated most of them lacked
domestic features. The lack of room features, such as
mealing bins or hearths, and the lack of artifacts suggest
they may have functioned as storage rooms.

14
Between A.D. 1075 and 1115, the east and west wings of
Pueblo Bonito were constructed, including this room. This
was the most extensive building phase in the canyon and one
of the last. There are several methods for dating and
identifying building phases including the science of
tree-ring dating known as "dendrochronology," and the
analysis of masonry styles and ground plans. The way walls
meet or "abut" is another method for identifying
construction sequences. Abutted walls do not interconnect
at corners but instead are flush with each other. Walls
that abut one another were constructed at different times,
while walls with stones that interconnect at the corners
were typically built at the same time.

15
Before wall building began, the layout of the structure was
determined by constructing foundations. If additions to the
original plan were made during construction, foundations were
added, while deletions from the plan left unused
foundations. Beneath the floors in this section of Pueblo
Bonito and extending to the east, a maze of unused wall
foundations have been located during excavations. They
consist of trenches that are about eighteen inches wide and
deep, filled with stone rubble set in clay
mortar. Foundations would have prevented uneven settling
of the walls and added durability.

16
There are at least four types of doorways that have been used
in great house construction; small doors with high sills,
large doors with low sills, corner doorways, and T-shaped
doors. The most common type is the small door with a high
sill and the most elegant is the T-shaped door. Although the
meaning of the T-shape is not clear, their placement appears
to be restricted to special locations in the buildings. They
usually open into plazas, or onto balconies or terraces.

17
You can see both original vigas and latillas in the well
preserved ceiling of this room. The upper-story floors and
exterior roofs of great houses consisted of large vigas,
latillas, split shakes, and layers of mortar and sand known
as "closing material." In 1991, cores and samples were taken
from these beams for tree-ring dating. Sampled areas are
visible as freshly sawed sites and circular depressions in the
vigas and latillas. When these beams were sampled, the latest
cutting dates were around A.D. 1082, indicating roof
construction sometime after that date.

18
If you turn around and look above and to the left of the rooms
you have just left, you will see a corner doorway. This is an
unusual type of door opening used in great house
construction. Only seven are known in Pueblo Bonito, and all
of them were built during later construction sequences in the
eastern part of the pueblo. This particular doorway appears to
function as an astronomical marker. When the sun rises on the
morning of the winter solstice, rays of sunlight pass through
this opening and strike the opposite corner of the room behind
it. Throughout the canyon, there are other architectural
features, as well as modified land forms, that correspond with
astronomical events. This knowledge of astronomy seems to have
been an integral part of the construction plan at Chaco.

The earthen mounds that you pass as you leave Pueblo Bonito
were originally identified as trash deposits, known as
"middens." Although they contain trash, they also include sand
and construction debris. These rectangular mounds are enclosed
by masonry walls raised about ten feet above the surrounding
ground level. The tops of the mounds were leveled, and they
were accessible via stairs. This combination of features
strongly suggests the mounds are planned architectural
features. Some archeologists believe these earthen mounds tie
in with the series of Anasazi roads and are part of the great
house landscaping. Similar mounds are found in association
with roads and formalized entrances to other great houses, such
as Pueblo Alto, Penasco Blanco, and Kin Ya'a.

Read More About It!

Frazier, Kendrick. People of Chaco, A Canyon and its
Culture. W.W. Norton and Company, Inc., 1986.